1. Field of the Invention
The subject invention relates to loudspeaker enclosures, and more particularly, to vented loudspeaker enclosures.
2. Description of the Related Art
It is difficult to provide a high quality loudspeaker reproduction of the lowest audio frequencies without resorting to large bulky enclosures.
One solution to this problem is the vented enclosure. U.S. Pat. No. 3,037,081 to Carlsson discloses such an enclosure in the form of an acoustic resonator in which the diaphragm of the loudspeaker forms a part of the wall of the resonator. The enclosure includes at least one port.
While such an enclosure has, at low frequencies, a smooth frequency response curve, good transient response and low non-linear distortion, the low frequency performance still tends to be lacking.
An object of the invention is to provide a loudspeaker enclosure which has small size and exhibits good low frequency performance.
A further object of the invention is to extend the low frequency response of a vented enclosure by at least one octave.
The above objects are achieved in a loudspeaker enclosure comprising a cabinet for containing a loudspeaker mounted in a wall of said cabinet, said loudspeaker facing away from an internal volume of said cabinet; a port mounted in a further wall of said cabinet; and acoustic resistive foam material positioned in front of said loudspeaker for limiting the amount of direct radiation from the loudspeaker thereby causing most of the usable acoustic radiation to emanate from said port.
Applicant has found that below the tuned frequency of a reflex enclosure, the driver and port radiation are in phase opposition which tends to cancel the usable acoustic output. By limiting the direct speaker radiation, the port radiation can extend the low frequency response by at least one octave.